Ni—Cr—Nb—P—B alloys capable of forming bulk metallic glass rods with critical rod diameters of 3 mm or greater have been disclosed in U.S. patent application Ser. No. 13/592,095, entitled “Bulk Nickel-Based Chromium and Phosphorus Bearing Metallic Glasses”, filed on Aug. 22, 2012, and Ser. No. 14/067,521, entitled “Bulk Nickel-Based Chromium and Phosphorus Bearing Metallic Glasses with High Toughness”, filed on Oct. 30, 2013, the disclosures of which are incorporated herein by reference in their entirety. In these applications, peaks in glass forming ability are identified at a Cr content ranging from 5 to 10 atomic percent, a Nb content ranging from 3 to 3.5 atomic percent, a B content of about 3 atomic percent, and a P content of about 16.5 atomic percent. Bulk metallic glass rods with diameters as large as 11 mm can be formed within those ranges.
The Nb and B atomic concentrations disclosed in those applications range from 1.5 to 4.5 atomic percent, for both Nb and B. Habazaki et al. has presented a Ni—Cr—Nb—P—B composition with a Nb concentration greater than 4.5 atomic percent capable of forming metallic glass rods 1 mm in diameter (H. Habazaki, H. Ukai, K. Izumiya, K. Hashimoto, Materials Science and Engineering A318, 77-86 (2001), the disclosure of which is incorporated herein by reference). However, those authors failed to demonstrate a compositional range at these higher Nb concentrations over which good glass-forming ability can be attained, where metallic glass rods can be formed with diameters of at least 3 mm. Furthermore, these authors failed to identify a compositional range over which good glass-forming ability in conjunction with unexpectedly high strength and/or thermal stability of the supercooled liquid can be attained.